Page 302 - AP Computer Science A, 7th edition

implemented and tested before being incorporated into the overall project. Typically, these are the basic objects of the program, like StockItem, Card, and BingoCard. U nrelat ed c las s es in a programming project can be implemented by different programmers.
Note that a class can be tested using a dummy Tester class that will be discarded when the methods of the class are working. Constructors, then methods, should be added, and tested, one at a time. A driver class that contains a main method can be used to test the program as you go. The purpose of the driver is to test the class fully before incorporating it as an object in a new class.
When each of the independent classes is working, classes that depend on just one other class are implemented and tested, and so on. This may lead to a working, bare bones version of the project. New features and enhancements can be added later.
Design flaws can be corrected at each stage of development. Remember, a design is never set in stone: It simply guides the implementation.
TOP-DOWN DEVELOPMENT
In a top-down design, the programmer starts with an overview of the program, selecting the highest-level controlling object and the tasks needed. During development of the program, subsidiary classes may be added to simplify existing classes.
Implementing Methods
PROCEDURAL ABSTRACTION
A good programmer avoids chunks of repeated code wherever possible. To this end, if several methods in a class require the same task, like a search or a swap, you should use helper methods. The reduce method in the Rational class is an example of such a